Prime Minister Malcolm Turnbull has used his speech at Garma to further defer any official response to the Referendum Council's recommendation of constitutionally enshrining a voice for Aboriginal Australians in Parliament.

Mr Turnbull said he accepted that many people involved in the Referendum Council's process wanted to see their recommendations implemented immediately, but urged for a careful consideration of how exactly they would be rolled out.

"The question is not if we should do these things, but when and how. We are not chained to the prejudices of the past. We cannot let the failure of [1999] govern the future of the constitution," he said.

Mr Shorten said agreeing on a referendum question should be the very next step and there was "no reason why that can't be done by the end of this year".

"The Parliament could agree on the question by the end of this year, with the referendum to follow soon after that," he said.

Mr Shorten later met with Indigenous leaders, including Referendum Council members Noel Pearson, Pat Anderson and Megan Davis, to assure them a Labor government would implement the council's full recommendations.

"They wanted to know that Labor was supportive of enshrining a voice for our first Australians in the constitution, I said we were," he said.

He said he was committed to delivering a referendum but also working with the Prime Minister for a bipartisan resolution.

"We are up for negotiation, compromise and debate, but the fundamental presumption is that we should have a process in this country where decisions that are made which affect Aboriginal and Torres Strait islanders are made with them not without them."